Boeing's 787 Dreamliner is designed to be a fuel-saving game changer.

NTSB

The passenger jet, which promises fuel savings through new composite materials and a powerful lithium-ion battery, has been out of service since the FAA issued an emergency airworthiness directive on January 16, following two incidents in which that battery failed.

Boeing is shrinking the lavatories on its 737 jets.

The standard economy class lavatory is three by three feet. Boeing is shrinking that in its 737 planes, thanks to a new design from B/E Aerospace.

Delta will be among the first to fly planes with the smaller facilities. The airline says passengers won't notice the difference, because the extra space has been removed from behind the sink, the Wall Street Journal reported.

Passengers are more likely to notice the four extra seats the smaller bathrooms make room for.

Sliding seats will get travelers off planes faster.

Sliding seats can reduce turnaround time, allowing planes to make more flights and save fuel while on the ground.

Former US Navy test pilot Hank Scott and aerospace engineer Kevin Van Liere created a sliding seat that will make aisles wider when it's time to deplane. The middle seat is set lower, so the aisle seat can slide over it.

There are downsides, however: The seats don't have much padding, and aren't meant for long-haul flights, according to USA Today.